migrations: add indexes for package_symbols and documentation_symbols

Indexes are added for the FKs on package_symbols and
documentation_symbols.

For golang/go#37102

Change-Id: I27ec5531e7fdc7ff89293b458554924b9e2e4b7f
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/299890
Trust: Julie Qiu <julie@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

migrations/000077_add_package_symbol_indexes.down.sql

@@ -0,0 +1,15 @@
+-- Copyright 2021 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+DROP INDEX idx_documentation_symbols_package_symbol_id;
+DROP INDEX idx_package_symbols_module_path_id;
+DROP INDEX idx_package_symbols_package_path_id;
+DROP INDEX idx_package_symbols_parent_symbol_name_id;
+DROP INDEX idx_package_symbols_symbol_name_id;
+DROP INDEX idx_package_symbols_section;
+DROP INDEX idx_package_symbols_type;
+
+END;

migrations/000077_add_package_symbol_indexes.up.sql

@@ -0,0 +1,15 @@
+-- Copyright 2021 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+CREATE INDEX idx_documentation_symbols_package_symbol_id ON documentation_symbols(package_symbol_id);
+CREATE INDEX idx_package_symbols_module_path_id ON package_symbols(module_path_id);
+CREATE INDEX idx_package_symbols_package_path_id ON package_symbols(package_path_id);
+CREATE INDEX idx_package_symbols_parent_symbol_name_id ON package_symbols(parent_symbol_name_id);
+CREATE INDEX idx_package_symbols_symbol_name_id ON package_symbols(symbol_name_id);
+CREATE INDEX idx_package_symbols_section ON package_symbols(section);
+CREATE INDEX idx_package_symbols_type ON package_symbols(type);
+
+END;